But, wait - what's that inside? I haven't a clue, but
it appears to be a copper wire "fence" that snakes around inside the body. Interestingly,
the wires are supported by posts that contact only the top of the guitar. So,
I suppose it was an interior "reverb unit" of sorts.

If by any chance you recognize this as a known maker's instrument,
the current owner would be grateful for any information.